Currently, it has been desired to promote energy saving at consumer's end, such as in buildings or houses. Furthermore, due to an influence of the earthquake disaster and tight power demand and supply, a solution for saving more energy (power saving) has been desired. Thus, it has been increasingly important to promote the energy saving at the consumer's end.
Recently, there is a discussion to introduce a “demand-response,” which suppresses a power consumption at the consumer's end, in a next generation power system (referred to as the Smart Grid). Here, the next generation power system is realized by establishing a communication environment between the power supplier's end and the power consumer's end. It is considered that, in the future, the energy saving at the consumer's end aiming for overall optimization of the power usage, such as adjustment or systematic stabilization of the power demand and supply, becomes more familiar.
In order to realize increasing the energy saving at the consumer's end, it is necessary to correctly understand environment of a room of the consumer. For example, an energy consumption of air conditioning related devices that maintain environment, such as a room temperature and room humidity, takes up approximately one fourth of the energy consumption of the entire office building. Thus, if excess heating or cooling is recognized and optimized, there is a possibility that large energy saving effect is obtained.
There is known an index referred to as a predicted mean vote (PMV), which is employed as a standard thermal comfort index (standard heat index) of the International Organization for Standard (ISO) 7730. The PMV is an index obtained by obtaining an unbalanced heat with respect to the environment, and by associating the unbalanced heat with thermal sensation. Accordingly, there has been proposed a technique to control air conditioning by using the PMV as a control index for the air conditioning, in order to improve comfort and to increase energy saving by removing the excess cooling and the heating.
However, in the conventional technology, there is no consideration on influence of a temperature change in a solar radiated article that directly receives solar radiation. Here, the solar radiated article is, for example a blind for blocking solar radiation from entering into a room via a window. Thus, the PMV estimated by the conventional technique might be different from that of the actual environment. If such PMV is used as the control index for the air conditioning or the like, there is a possibility that a predicted room environment of the air conditioning or an energy saving effect cannot be obtained.